bhod - BSU program to solve for borehole tool orientation by PCA
bhod [ -h | infile | chR | chT | ipct | saz | azctl | tsw1 ]
Basic Seismic Utilities (BSU) uses Principal Component Analysis (PCA) to determine a borehole tool orientation from the large particle motion observed on the horizontal components. The seismic source should be capable of generating SH-waves. The program generates Postscript QC plots of particle motion, as well as a file, bhod.lst, which contains triplets specifying file seequence number, R-component azimuth, and T-component azimuth. The file, bhod.lst, is used by program btor to apply the azimuth determinations to the trace headers. A program, genbhod, can be used to generate bash scripts which permit batch processing by bhod. Code is in Fortran 77.
Options
|
-h |
Online help giving details on command line arguments | ||
|
infile |
Input file name. | ||
|
chR |
Channel number corresponding to R-component | ||
|
chT |
Channel number corresponding to T-component | ||
|
ipct |
Percent of peak motion modulus. To be included in PCA, sample amplitude must be > ipct. | ||
|
saz |
SH-wave source axis (particle motion). An East-West alignment would be indicated by 90 degrees. | ||
|
azctl |
Typically the azimuth of R-component on exiting the borehole. This is a vector which resolves the ambiguity (180 degree) in PCA. This forces the R-component result to be the direction closest to azctl. | ||
|
tsw1 |
Switch to set T-component azimuth relative to R-component. The T-component azimuth will be |
T_azim=R_azim + tsw1
With the author’s recording configuration, tsw1=+90 for his down-hole tool, tsw1=-90 for the reference phone at the surface. This is because the two tools are of opposite chirality.
NOTE:
If invoked with no options, will prompt user for input
parameters.
EXAMPLE:
bhod h002001.seg 2 3 50 90.0 315.0 +90.0
A program genbhod generates a script. That script is gorunbhod, and the above example is representative of a typical instruction. The program genbhod also generates a script, gobhodo which is run first. It combines opposite source polarity efforts at each subsurface station to produce an SH-wave enhanced file, h002001.seg in this case. The SH-enhanced input file is formed by scaling the the two shot records on the peak vertical motion, and then subtracting in an attempt to null out Rayleigh and P-waves. A description of the process can be found in Michaels (2001).
xxxxplt.ps
Postscript QC plot of PCA. Naming convention (first 4char are from first 4 char of infile, the last characters are always plt.ps). For the example, it would be, h002plt.ps.
standard output
produces a progress bar
bhodxxxx.lst
Echo check of input parameters in listing file, and details of PCA analysis for input file.
bhod.lst
File with triplets [sequence number, R-azimuth, T-azimuth]. This is input to btor.
bhelp(1), bsegy(5), btor(1), brot(1), polarity(5), genbhod(1)
Michaels, P. (2001), "Use of Principal Component Analysis to Determine Down-hole Tool
Orientation and Enhance SH-Waves", Journal of Environmental and Engineering
Geophysics, Volume 6, Issue 4, p. 175-183.
no known bugs
Copyright © 2024 by Paul Michaels
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
P. Michaels, PE. <[email protected]>